PHOTOLYTIC AND OXIDATIVE-DEGRADATION OF AN ANTIEMETIC AGENT, RG-12915

RG 12915 (I) undergoes dechlorination and substitution in aqueous solu tions when exposed to an artificial daylight fluorescent light. The fr ee-radical photodecomposition exhibits apparent first-order kinetics a t all concentrations and the reaction proceeds faster in dilute soluti ons. The drug substance is also susceptible to oxidative degradation. Oxidation occurs on the benzofuran moiety as well as on the quinuclidi ne moiety. Auto-oxidation on the benzofuran moiety produces a correspo nding hydroperoxide. Subsequent decomposition of the hydroperoxide giv es rise to the secondary oxidation product, the hydroxy compound. The oxidative free-radical reaction shows an induction period, followed by a period of accelerating degradation and eventual leveling off. The o xidation reaction proceeds faster in concentrated solutions and at low er pH, and is accelerated by cupric ion. EDTA prevents the oxidative d egradation of the drug substance. Propyl gallate inhibits the oxidatio n of the benzofuran moiety but not N-oxide formation.